Oftentimes it is necessary for an airplane to determine the geolocation of a radio frequency (RF) emitter, for example, a radar station. As shown in FIGS. 1.1-1.3, a side-view, top-view and front-view of an airplane 100, respectively, a number of antennas, i.e., signal receivers, 104.1-104.4 are provided on the plane 100. Two of the antennas 104.1, 104.2 are provided on a fuselage 108 while the other two antennas 104.3, 104.4 are provided on a respective wing 112.1, 112.2. The antennas 104 are provided to detect a signal being transmitted from an emitter such as, for example, a radar station. In addition, an Inertial Navigation System (INS) 116, the operation of which is well known, is provided on the airplane 100 and is used, in combination with the signals detected by the antennas 104, to determine a location of the radar station with respect to the airplane 100.
It is well known, however, that the wings 112 of modern airplanes 100 can move significantly with respect to the fuselage 108 as represented by the arrows W shown in FIG. 1.3. For an airplane such as, for example, a Boeing 767, about 166 feet long with a wingspan of about 158 feet, the tips of the wings can “flex” or move around several inches, which is comparable to a typical RF wavelength of a radar station emission. As a result, the signals received at the antennas 104 on the wings 112 will introduce significant errors into the determination of location as the displacement, due to the flexing, of the wings 112 with respect to the antennas mounted on the fuselage 108.
Due to the flexure of the wings, known geolocation systems have been provided with either relaxed requirements, i.e., reduced accuracy requirements, and/or have been limited to platforms with shorter and stiffer wings in order to shorten the baselines.
Accordingly, what is needed is a way to make the determination of the location of a signal emitting station, as detected by antennas on a flexible platform, more accurate.